Combined branch retinal artery and branch retinal vein occlusion from a globe penetrating nail gun injury

Background: Nail gun injuries represent a significant proportion of work-related ocular trauma. Here we report a rare case of a combined branch retinal arterial occlusion (BRAO) and branch retinal venous occlusion (BRVO) from a nail gun injury in a patient who was wearing eye protection. Case description: A 23-year-old male presented with a left globe penetrating injury from a pneumatic nail gun. The nail ricochet bypassed the patient’s protective eyewear, penetrating the left globe causing multiple retinal tears and a combined BRAO and BRVO in the inferior temporal vascular arcade. The patient underwent prompt surgical repair obtaining an excellent anatomic outcome. However, the visual outcome was 20/200 OS at one and two years post injury primarily due to extensive ischemic damage of the retina. Conclusion: This case is the first to describe a combined BRAO and BRVO from a globe penetrating injury. What makes this case even rarer is that the patient was wearing eye protection at the time of the injury. Despite appropriate emergency management, rapid referral for ophthalmologist assessment, and timely surgical management of this patient, the visual outcome was poor. The vascular injury ultimately compromised a significant segment of the retina, including the macula.


Background
Ocular trauma from globe penetrating injury and intraocular foreign bodies (IOFBs) constitute approximately 17-44% of cases of significant vision impairing traumatic ocular injury [1], [2]. Ocular trauma is a major cause of monocular blindness worldwide and the second most common cause of visual impairment in the United States [1], [3], with nail-related eye injury accounting for approximately 5% of major eye injuries [4]. The use of pneumatic nail guns is common place in carpentry and construction. Despite strict safety guidelines with the correct operation requiring the use of safety glasses, the rates of non-compliance with safety glasses in the literature range from 56% to 94% [5], [6], [7], [8], [9]. There are few reports of significant ocular injury in patients wearing correct personal protective equipment (PPE). In a recent study looking at 603 eye injuries, only 3 patients were wearing PPE at the time of the injury [10]. Here we present an unusual case of a man who sustained a work-related globe penetrating injury from a nail fired from a pneumatic nail gun causing a combined branch retinal arterial and branch retinal vein occlusion (BRAO and BRVO). Interestingly, the patient was wearing eye protection and this injury was sustained by a nail ricochet that bypassed the patient's safety glasses, penetrating the globe inferionasally.

Case description
A 23-year-old male presented to the emergency department following a work-related globe penetrating injury from a pneumatic nail gun to his left eye (OS) 4 mm inferionasally from the limbus (Figure 1a). At the time of the injury, the patient was operating a pneumatic nail gun in an overhead position at a housing contraction site in Ontario Canada. The patient was wearing standard eye protective glasses (polycarbonate lenses, CSA approved) at the time of the nail ricochet. He was promptly referred to Ophthalmology for emergency nail removal and primary closure and subsequently underwent retinal specialist review 3 days later.

On examination
Best corrected visual acuity (BCVA) was 20/20 OD and 20/70 OS. Pupils were 5 mm OD and 6 mm OS. The left pupil was nonreactive to direct light; with no relative afferent papillary defect. Extraocular movements and intraocular pressures were normal. Slit-lamp examination Operative repair 11 days after the injury the patient underwent 23G vitrectomy combined with cataract extraction with IOL, scleral buckle, silicone oil tamponade and laser endophotocoagulation without complication. Five days post-surgery BCVA was 20/100 OS with no SRF on examination and OCT. Silicone oil was removed 3 months later and replaced with SF6 gas without complication.

Visual outcome
Over the next 4 months, the patient complained of increasing blurred vision OS which decreased from best corrected visual acuity of 20/100 OS to 20/400 OS. Increased capsular haze was noted and treated with a YAG laser capsulotomy. Despite a good surgical outcome, BCVA 1 year after injury was 20/400 OS with scaring and atrophy evident in the inferior retina (Figure 2a,b). Extensive attenuation of the inferior vascular arcade was noted compared to the time of injury (Figure 2b,c). The extent of tissue ischemia from the vascular injury is likely responsible for the patient's poor visual outcome.

Discussion
Eye injury from nails accounts for approximately 5% of all major eye injuries [4], with a large proportion of these injuries being associated with nail guns. In the majority of cases, ocular nail gun injuries are associated with the lack of proper personal protection equipment (PPE) or the improper use of such equipment [3]. Interestingly, our patient had been wearing eye protection at the time of injury with the mechanism most likely due to the nail ricocheting at an angle that bypassed his PPE. Nail ricochet is common and represent 37% of nail gun related eye injuries [3]. Nail guns can propel nails with a velocity of 100-150 m/s [11] causing them to act as missiles. Typically, injuries caused by nail guns produce less contusive damage to the retina versus blunt force-type injuries and therefore are often less severe than expected [12]. Ricochet injuries are less predictable because the nail is commonly bent [11] and the trajectory can be complicated by rotational forces. Although studies suggest favourable visual acuity is achieved in the majority of nail gun injury cases [3], patients with posterior segment injury tend to have worse visual outcomes [3]. In our patient, there was extensive retinal detachment with a large tear encroaching on the periphery of the inferior macular region. However, even with the direct retinal trauma the majority of the macula and fovea appeared to be spared from direct trauma. Unfortunately for our patient, the nail also disrupted the arterial and venous supply to the inferior portion of the retina leading to secondary ischemic damage.

Conclusions
This case is unusual because reports of traumatic combined BRAO and BRVO are rare, with only one other report in the literature [13] and there are no reports of such an injury occurring with the use of PPE. What is rarer still is that the nail did not break the safety-lens but rather the angle of ricochet allowed the nail to enter the globe from below the safety-glasses, unimpeded by the lens. This injury reinforces the importance of workplace education on the proper usage of nail guns as well as the proper use of PPE and demonstrates that despite prompt and appropriate medical and surgical treatment, globe penetrating trauma can have catastrophic sequelae.

Notes Patient consent
The patient has viewed the content and images of this case report and has consented to the submission of the case report for publication.